Ignition timer



Jan. 26, 1943. s. M. UDALE IGNITION TIMER Filed lay 8, 1942 2Sheets-Sheet l S. M. UDALE IGNITION TIMER Filed Ily 'B, 1942 Jan 26,1943.

' 2 Sheets-Sheet 2 INVENTOR.

1 E Q hm f M Patented James, 1943 UNITED STATES PATENT OFFICE IGNITIONTIMER Stanley M. Udale, Detroit, Micln, assignor -to George M. Holleyand Earl Holley Application May a, 1942, Serial No. 442,199

3 Claims.

This application is a continuation inpart-of application Serial No.334,329, filed May 10, 1940, entitled Torque controlled engine.

Theobject of this invention is to adjust the spark for maximum mileageon an airplane englne. In an airplane engine it has been found desirableto have a retarded spark when the enspark has frequently been used fornormal and abnormal rlmning so that the spark was not advanced as far asit may have been if maximum mileage were the only objective.

In the drawings:

in the cylinder 23 which carries a compression spring 2! so that thepressure in the cylinder I3 is balanced by the compression of the spring2|. The cylinder 23 carries a collar 22 with which engages a pin 23projecting from a manually controlled lever 24 which is controlled bythe manually controlled rod 25. This lever 24 is connected by a one-wayconnection 4| with the lever l1 and the limit to the opening movement ofthe lever 24 is determined by an adjustable stop 40, which stop 40serves as a torque control for the engine and therefore indirectlyserves as a power control.

Fig. 1 shows diagrammatically an air cooled I engine having a torqueresponsive device.

Fig. 2 shows the control means for the carburetor and ignition devicescontrolled by the torque responsive means 01 Fig. 1.

Fig. 3 shows the carburetor attached to a con- -ventional engine havinga supercharger and torque control.

Fig. 4 shows the end view of the torque control.

The invention is shown diagrammatically in the drawings in which aradial air-cooled engine is shown diagrammatically at II on which ismounted a torque-responsive device II, a supercharger 43 and amixture'outlet 44 which delivers an explosive mixture to thesupercharger 43. This engine I! and supercharger 43 are drawn to a smallscale whereas Fig. 2 is drawn to a larger scale. The torque-responsivedevice is connected by a pipe II which is therefore shown to a smallscale in Fig. 1 and to a larger scale in P18. 2.

The pipe l2 communicates with the cylinder l3 in which reciprocates apiston l4 which constitutes a torque control. The torque indicatingdevice corresponds to one of those described in the S. A. E. Journal forJune, 1939, pages 271 to 276 and specifically to Fig. 4, on page 273,and is made sufficiently powerful so that it can operate the piston II.This piston l4 carries a collar II with which engages a pin I3projecting from the y the rod lever II. This lever II is connected 13with the throttle II. The P ton i4 is guided The carburetor is showndiagrammatically having an anterior throttle l3, a fuel and air nozzle35 which is supplied with a small quantity of air admitted through arestricted orifice 36 and is supplied with fuel through a restrictedfuel entrance 4! controlled by a needle valve 46 which, in its turn, iscontrolled by partially evacuated aneroid capsules 32. A float 3! islocated in the float chamber '41, which chamber is subjected to theinlet manifold suction and controls the float .mechanism whichsuppliesfuel to this constant level supply chamber 41. A piston 33 isshown located in the cylinder 83 connected by a pipe with the cylinderl3. This piston 33 is held in position shown by a preloaded spring 33and carries a metering valve 34 which admits extra fuel to the fuelnozzle when the maximum torque is reached and exceeded. This valve 34 isactually much smaller than the valve shown. A one-way link 33 isconnected to an arm 33 of a circuit breaker plate 33 so as to rotate thecircuit breaker and so retard the spark slightly when maximum torque isrecorded.

In order to retard the spark so that the engine may be started safely aspring l engages with the rod 33 and pulls the circuit breaker 30clockwise so that it engages with the stop 42.

A second torque-responsive piston 31 is located in a second cylinder andconnected by a link so with an arm. 33 of the circuit breaker v3ll. Theupper portion of this second cylinder is connected to the lower part ofthe cylinder 83 through an open passage.

Whenever the engine-is running the piston 3| is pushed down by thetorque-responsive pressure existing above the piston II and the springii being relatively weak yields and the circuit breaker 33 is thusrotated anti-clockwise until it engages with the stop II, which is thefully advanced position of the timer.

The link 3| slides through a rotatable pin 32 mounted on the arm II. Thetorque pressures that at all altitudes, some torque will be developedwith the throttle l9 partly open. Hence there will be a substantialpressure on the piston 9| which will fully advance the spark. The torquepressure in the cylinder 13 acting on the piston 33 will compress thepreloaded spring 89, which spring tends to hold the valve 34 closed. Thetorque pressures are designed to be sufliciently powerful to overcomethe efiect of the spring H.

At extremely high altitudes with the throttle l9 wide open, the torquepressures in the chamber can no longer maintain its maximum torque, thefuel needle valve 34 closes and the rod 33 descends and the torquepressure in I3 is no longer operative to retard the spark, Under theseconditions, the circuit breaker 30 is maintained in contact with thestop 8| until such time as the torque pressure in I3 is suflicientlygreat to raise the rod 33 to retard the spark. Under these conditions,the spring II is made sufliciently weak so that the pressure in thecylinder I3 when it overcomes the preloaded spring 89, is only modifiedslightly by the spring H and the retardation is mainly controlled by thepressure responsive torque existing in the cylinder I3.

I3 will not be sufliciently powerful to compress the spring 33 and thespark will be fully advanced.

In Fig. 3-the carburetor is shown connected through the pipe 44 with thesupercharger 50 contained within the housing 43. This supercharger isdriven by a crank shaft 5| connected with a piston 52 which reciprocatesin the cylinder 53 having the usual inlet and outlet valves 54 and 55.The spark control rod- 38 is shown connected to the circuit breakerplate 30, and the circuit breaker itself is shown driven by the two toone gears 55 and 51. The details of the torque control are copied frompage 273 of the'June, 1939, number of the S. A. E. Journal, Figure 4,and consist of the following:

An internal gear 58 driven by the crank shaft 5| drives an external gear59 which is connected to the diamond-shaped piece 60 which is connectedthrough the connecting rods GI and 82 to the pistons 63 and 84. A valve65 admits high pressure oil to the line 65. The pressure in the pipe 6'!is thus automatically maintained equal to that of the torque created bythe engine. The high pressure oil, the pressure of which varies with thetorque, is connected through the pipe H to the apparatus shown in Fig.2. The propeller take-oil is through the shaft 68 which carries the arm53 upon which are mounted gears in, III, which engage with both theexternal gear 58 and the internal gear 59. Any torque that may beapplied to the propeller on the shaft 68 is transmitted through theshaft 68 to the spider 69 which carries the pinion 10. If the torquegoes up, the pressure in the pipe l2 goes up, and vice versa. 7

Operation When the manually controlled lever 24 is moved to the left toopen the throttle [9 by compressing the spring 2|, the engine runs withthe throttle l9 wide open until the torque responsive device H createssufilcient pressure so as to compress the spring 2| and thus close thethrottle l9 until the torque created in the device II just balances thecompression of the spring 2| which is determined by the adjustment ofthe lever 24. If the plane is now flown to the normal heights for whichthese engines are designed to operate,

. namely two or three miles above sea level, the

throttle l8 will gradually open in order to maintain the torquedetermined by the position of the lever 24 and this will continue untilthe throttle I9 is wide open, and thereafter the torque will fall as theair density falls, until finally the plane can climb no more because thepower is not great enough and the air density is too low to support theplane. a

When the plane reaches the point at which it The link 91. is pivotallyconnected to the lever SI and serves as a piston rod for the piston 3|which is substantially the same area as the piston 32 and is subjectedto the same pressure; The piston 91 is supported by the relatively lightspring 1| so that at relatively low torque the piston. 9| descends andadvances the spark. When excessive pressures exist in 83, the piston 32overcomes the piston because the piston 32 acts at a longer leverage onthe arm 80. Hence, the pi'ston 9| is moved upwardly despite the increaseof pressure. when the engine is not running the spring H takes over andretards the spark. The moment the engine fires, and the throttle ismoved the slightest degree away from idle, torque is developed andimmediately torque is developed, the piston 9| moves down compressingthe spring H and the spark is fully advanced and the circuit breaker 30engages with the stop 8|.

What I claim is:

1. An ignition timer for an internal combustion engine having a torqueindicating device, comprising a yieldable means for retarding theignition timer, means responsive to the operation of the engine forovercoming said yieldable means so as to advance the spark, torqueresponsive means for retarding the ignition timer, said torqueresponsive means being inoperative until the torque exceedssubstantially 70% of the rated torque of the engine.

2. An ignition tuner for an internal combustion engine having a torqueindicating device, comprising yieldable means for retarding the ignitionwhen the engine is not running, torque responsive means for overpoweringsaid yieldable means so as to advance tue ignition timer whenever anysubstantial torque pressure is developed in the torque indicatingdevice, additional torque responsive means responsive only to torques inexcess or substantially 40% of the rated torque of the engine forretarding the ignition timer, said second mentioned torque responsivemeans having a mechanical advantage over the first mentioned torqueresponsive means.

3. An ignition timer 101 an internal combustron engine having a torqueindicating device and a carburetor having an an entrance and a throtuevalve controlling the how through said entrance, comprising meansindependent of said throttle for holding said timer in the advancedposition under all normal engine operating conditions, torque responsivetiming means adapted to retard but not to advance the time of ignitionand operative when the torque developed by the engine exceeds 70% of theengines rated torque and said torque responsive and ignition retardingmeans being adapted to,overpower said advancing means so as to retardsaid time of ignition during periods of excessive torque.

STANLEY M. UDALE.

